A rocket engine is a device that produces a force by pushing gases at high speed out of a nozzle. Rocket engines usually burn chemicals such as petrochemicals and liquid oxygen at very high pressures and temperatures to turn their chemical energy into motion of the rocket. In some cases (such as the Rocketdyne F-1), the force created can be over Lua error in Module:Convert at line 1850: attempt to index local 'en_value' (a nil value)..